Support Case Agent API Compatibility #342

Problem

The Support Case Management Agent cannot be evaluated in the framework because its API format is incompatible:

What the agent has:

• SSE-based streaming endpoint (POST /chat)
• Conversation ID in the final SSE event, not response headers
• Custom event types (assistant_message, tool_calls, done)

What the framework expects:

• Standard REST endpoint or generic HTTP streaming
• Conversation ID in headers or top-level JSON field
• Generic chunk-based streaming

Impact: Without conversation_id from the response, trace capture (#338) cannot work — the LangFuse adapter needs conversation_id to query traces.

Solution

Add support for SSE streaming with custom event types. Allow agents to specify endpoint_type: "chat_stream" to indicate SSE format with typed events.

How it works:

1. Framework sends POST /chat with JSON body {"query": "...", "conversation_id": "..."}
2. Agent streams SSE events: assistant_message, tool_calls, done
3. Framework extracts conversation_id from final event (done or last assistant_message)
4. Framework populates TurnData: response content, tool_calls, tokens, conversation_id

Success Criteria

• New config option: endpoint_type: "chat_stream"

• SSE parser handles event: <type> and data: <json> format

• Conversation ID extracted from final event

• Tool calls aggregated from tool_calls events

• Token usage extracted from done event

• Errors from error events captured

• Existing endpoint_type: "chat" behavior unchanged

• Support Case Agent can run full evaluations with trace capture

  Dependencies

  Blocks: Issue Trace Ingestion from Observability Platforms #338 trace capture — LangFuse adapter needs conversation_id correlation

  Example Configuration

  agents:
    support_case:
      type: http_api
      api_base: http://support-api:8000
      endpoint: /chat
      endpoint_type: chat_stream   # Handles SSE format
      trace_source: langfuse_traces
  
  Out of Scope
  
  - Changes to Support Case Agent API (use existing format)
  - Generic SSE support for all agents (agent-specific event types)